The present invention relates to a method of printing a set of consecutive original pages on a number of receiving sheets, either in a first printing mode in which in each case one page is printed on each side of a receiving sheet, or in a second printing mode in which two pages can be printed next to one another on each side of a receiving sheet and the receiving sheets are then double-folded to form a booklet.
A method of this kind is known from Xerox Disclosure Journal, July/August 1987, No. 4, pp. 179-180.
According to this known method, in the second printing mode for forming a booklet the first receiving sheet printed is the one which carries the first page of the required booklet. For a 12-page booklet the twelfth original page together with the first original page is printed first on a receiving sheet. In the case of automatic feed of original sheets from the bottom of a stack of original sheets, the originals are situated with pages numbers 1 and 12 at the bottom.
As a result of the increasing availability of printing apparatus with which folded booklets can be made, there will also be an increasing demand for making a copy of such a booklet. In order to use the above-mentioned known apparatus for this purpose, the folded booklet must be unfolded so that it can be put in in the form of a stack of original sheets. One disadvantage in this connection is that it is difficult to press the unfolded booklet flat, so that the sides of the booklet with the first page at the bottom project up and render separation of the original sheets difficult.
The object of the present invention is to provide a method without this disadvantage.
To this end, and for the purpose of printing a set of consecutive original sheets in the first printing mode, the first receiving sheet to be printed is a sheet that will form the front of the set, and therefore contains the first page, and for the purpose of printing a set of original sheets formed as a booklet, the first receiving sheet to be printed is the sheet that forms the center of the booklet and the last sheet to be printed is the receiving sheet which forms the outside of the booklet, and therefore contains the first page.
As a result, for the method of copying a booklet to form a booklet, use can be made of a printing apparatus in which original sheets of an unfolded booklet can be reliably separated from the bottom of a stack, i.e., when the originals are situated with their fold line disposed transversely of the feed direction of the originals.
Preferably, in the case of the printing of receiving sheets on both sides, in the first printing mode, in each case, first a predetermined side of a receiving sheet is printed and only then is the other side of said receiving sheet printed and in the second printing mode, in each case, a receiving sheet is first printed on the side which corresponds to the predetermined side in the first printing mode and only then the other side.
The effect of this is that when oriented receiving material is used, e.g. receiving material where at the side forming the front of a set of prints has a different surface color and/or texture from the other side, both printing modes have the result that the first page of the set comes on the same side of the receiving material without the receiving material having to be fed differently according to the printing mode that has been set.
The present invention also relates to a printing apparatus for performing the above method. Preferably, the printing apparatus comprises control means which automatically set the printing apparatus to the second printing mode when the printing apparatus for making a booklet is only set to double-folding and possibly stapling of a printed set of receiving sheets.
Consequently, the printing apparatus can immediately start printing the required booklet when the bottom original sheet forming the center of the unfolded booklet is separated from the rest of the stacked original sheets of the booklet for copying and has been scanned for printing.
In the case of introduction of a set of original sheets, each carrying one page, the printing apparatus must, in fact, be set to printing in a different page order from the page order in which the original sheets were scanned. For this purpose it is necessary that all the original sheets of a set should first be scanned before printing can start.
According to another aspect of the present invention, the control means also set the printing apparatus to the second printing mode when the printing apparatus for making a booklet of a set of original sheets each containing one page on a side has been set to a printing order adapted thereto.